I have couple of hard lumps on my shin the size of a pea, it only hurts a bit at night. what could it be as my mum's not caring.

Two ideas: If just below the knee & at the top/front of the bone, this is the insertion site for your knee stretching muscles. While you still have some linear growth left that point can be soft/painful because it is not firm bone yet. When growth stops it will firm up and become part of the bone & stop being sensitive. If located elsewhere it could be from random trauma. Neither are worth worry.